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13 Jul 2008, 17:00

Virtually everything astronomers known about objects outside the solar system is based on the detection of photons—quanta of electromagnetic radiation. Yet there is another form of radiation that permeates the universe: neutrinos. With (as its name implies) no electric charge, and negligible mass, the neutrino interacts with other particles so rarely that a neutrino can cross the entire universe, even traversing substantial aggregations of matter, without being absorbed or even deflected. Neutrinos can thus escape from regions of space where light and other kinds of electromagnetic radiation are blocked by matter. Furthermore, neutrinos carry with them information about the site and circumstances of their production: therefore, the detection of cosmic neutrinos could provide new information about a wide variety of cosmic phenomena and about the history of the universe.But how can scientists detect a particle that interacts so infrequently with other matter? Twenty-five years passed between Pauli’s hypothesis that the neutrino existed and its actual detection: since then virtually all research with neutrinos has been with neutrinos created artificially in large particle accelerators and studied under neutrino microscopes. But a neutrino telescope, capable of detecting cosmic neutrinos, is difficult to construct. No apparatus can detect neutrinos unless it is extremely massive, because great mass is synonymous with huge numbers of nucleons (neutrons and protons), and the more massive the detector, the greater the probability of one of its nucleon’s reacting with a neutrino. In addition, the apparatus must be sufficiently shielded from the interfering effects of other particles.Fortunately, a group of astrophysicists has proposed a means of detecting cosmic neutrinos by harnessing the mass of the ocean. Named DUMAND, for Deep Underwater Muon and Neutrino Detector, the project calls for placing an array of light sensors at a depth of five kilometers under the ocean surface. The detecting medium is the seawater itself: when a neutrino interacts with a particle in an atom of seawater, the result is a cascade of electrically charged particles and a flash of light that can be detected by the sensors. The five kilometers of seawater above the sensors will shield them from the interfering effects of other high-energy particles raining down through the atmosphere.The strongest motivation for the DUMAND project is that it will exploit an important source of information about the universe. The extension of astronomy from visible light to radio waves to x-rays and gamma rays never failed to lead to the discovery of unusual objects such as radio galaxies, quasars, and pulsars. Each of these discoveries came as a surprise. Neutrino astronomy will doubtless bring its own share of surprises.

3. In the last paragraph, the author describes the development of astronomy in order to(A) suggest that the potential findings of neutrino astronomy can be seen as part of a series of astronomical successes(B) illustrate the role of surprise in scientific discovery(C) demonstrate the effectiveness of the DUMAND apparatus in detecting neutrinos(D) name some cosmic phenomena that neutrino astronomy will illuminate(E) contrast the motivation of earlier astronomers with that of the astrophysicists working on the DUMAND project7. The passage mentions which of the following as a reason that neutrinos are hard to detect?(A) Their pervasiveness in the universe(B) Their ability to escape from different regions of space(C) Their inability to penetrate dense matter(D) The similarity of their structure to that of nucleons(E) The infrequency of their interaction with other matter8. According to the passage, the interaction of a neutrino with other matter can produce(A) particles that are neutral and massive(B) a form of radiation that permeates the universe(C) inaccurate information about the site and circumstances of the neutrino’s production(D) charged particles and light(E) a situation in which light and other forms of electromagnetic radiation are blocked9. According to the passage, one of the methods used to establish the properties of neutrinos was(A) detection of photons(B) observation of the interaction of neutrinos with gamma rays(C) observation of neutrinos that were artificially created(D) measurement of neutrinos that interacted with particles of seawater(E) experiments with electromagnetic radiation

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13 Jul 2008, 18:06

3. In the last paragraph, the author describes the development of astronomy in order to(A) suggest that the potential findings of neutrino astronomy can be seen as part of a series of astronomical successesSeems correct.

(B) illustrate the role of surprise in scientific discoveryAuthor is not interested in putting surprise as important, rather he is saying neutrino research will bring surprise.

(C) demonstrate the effectiveness of the DUMAND apparatus in detecting neutrinosHe is putting effectiveness of neutrinos research as a whole, not necessarily only DUMAND project.

(D) name some cosmic phenomena that neutrino astronomy will illuminateAuthor does not name any phenoma.

(E) contrast the motivation of earlier astronomers with that of the astrophysicists working on the DUMAND projectNo contrast is presented.

7. The passage mentions which of the following as a reason that neutrinos are hard to detect?(A) Their pervasiveness in the universeMay be that is the case, but not supported in passage.

(B) Their ability to escape from different regions of spaceYes it is true, but questions is exactly asking this why do they escape. So it is question?

(C) Their inability to penetrate dense matterIt is reverse of what is supported in passage.

(D) The similarity of their structure to that of nucleonsNot true.

(E) The infrequency of their interaction with other matterYep, this is the answer.

8. According to the passage, the interaction of a neutrino with other matter can produce(A) particles that are neutral and massiveNot supported.

(B) a form of radiation that permeates the universeNot supported.

(C) inaccurate information about the site and circumstances of the neutrino’s productionNot supported.

(D) charged particles and lightYep. As mentioned in passage "when a neutrino interacts with a particle in an atom of seawater, the result is a cascade of electrically charged particles and a flash of light that can be detected by the sensors"

(E) a situation in which light and other forms of electromagnetic radiation are blockedNot supported.

9. According to the passage, one of the methods used to establish the properties of neutrinos was(A) detection of photonsNot supported.

(B) observation of the interaction of neutrinos with gamma raysNot supported.

(C) observation of neutrinos that were artificially createdYes, as mentioned in paragraph 1 "virtually all research with neutrinos has been with neutrinos created artificially in large particle accelerators and studied under neutrino microscopes".

(D) measurement of neutrinos that interacted with particles of seawaterNot true.